Hey All, I am a mail carrier and have an unusual problem that I have not seen addressed anywhere else on the internet. On a cool temperature day, my blazer will run my 6 hour route with no problems whatsoever. However, on a hot day, after about 1 to 2 hours, my fuel pump starts whining really loudly. Then, after about another hour, the blazer will sputter and shut off, whether I am pressing the gas or coming to a stop at someone's mailbox. I have replaced the fuel pump, fuel filter, fuel pump relay, radiator, distributor cap, idle air control module, thermostat, throttle body module sensor... have had the catalytic converter rodded out.... heavy duty fan cluth put in.... fuel pressure and fuel pump grounding test fine, even when whining (approx 57 to 59 on pressure).... WHEN it shuts off, sometimes it will crank right back up and run anywhere from 10 minutes to 45 minutes.... sometimes, it will have to sit about 5 minutes before I can get it to crank again.... BUT if I am riding down the road and NOT stopping for several minutes, it runs fine, NO problems... I have been told that SOMETHING is getting hot, but there is no way to put an extra fan in there to keep things cool... Have been through 6 mechanics, including 2 Chevrolet mechanics, NO CODES SHOWING UP.... Can anyone help???